Whether we’re talking about a great novelist like John Irving or an era-defining entrepreneur like Jeff Bezos, it’s natural to conclude that the mega-successful owe their achievements to an almost magical quality that you’re either born with or you’re not: talent.

But according to Angela Duckworth, the University of Pennsylvania psychologist who’s made it her life’s goal to help children thrive, this is mistaken. Yes, the aptitude you bring is important, but few of us ever reach the limits of our natural abilities. Instead what holds us back is a lack of commitment or a lack of focus. “Enthusiasm is common,” Duckworth writes, “endurance is rare.”